In a yarn feeder which is known from EP 0 446 447 A1, the support body is a movable slide which is movable in the extension arm by means of a compressed-air/cylinder/piston unit. A spring is accommodated in the cylinder and acts on the piston in a direction opposite to the compressed-air action. The piston rod is coupled via a hinge to an adjusting screw which has fixed thereon the movable slide which is supported in the guide tracks of the extension arm and separated from the piston. The movable slide guides the holder of the yarn braking body which is adjustable by means of an adjusting screw relative to the movable slide. Great constructional efforts are required for guiding the movable slide in the extension arm and the holder on the movable slide. The strong soiling caused by depositing yarn material, the relatively great reactive forces of the support of the yarn braking body on the storage body, which slightly vibrates during operation, unavoidable wear in the various guide tracks, the multipart structure of the holding device and the necessity of an easy adjustability of the yarn braking body with an exactly reproducible braking position might lead to problems because of which the gap position and/or the braking position cannot be adjusted in the predetermined manner. Furthermore, the versatile holding device requires considerable constructional space.
It is the object of the present invention to provide a yarn feeder of the above-mentioned type in which the holding device is simple under manufacturing and assembling aspects and is only composed of a few parts and can guarantee the predetermined position of the yarn braking body in a reliable manner in the case of both frequent and rare adjusting operations.